Heat-generating element cooling device

ABSTRACT

A cooling device mounting a fan unit above a heat sink mounted on a heat-generating element or buried therein, which produces an effective air flow and achieves a uniform cooling action by having the heat sink shown in various shapes. Further, a cooling fan disposed away from the heat sink or to the side of the same is used for effective cooling through an air conduit passage formed by pipes or a cover.

This is a division of application Ser. No. 08/211,241, filed Mar. 29,1994, U.S. Pat. No. 5,583,316.

TECHNICAL FIELD

The present invention relates to a cooling device for cooling aheat-generating element or a heat-generating unit, that is, a heat sinksystem, more particularly relates to a heat-generating element coolingdevice for cooling a heat-generating element or heat-generating unitsuch as a high density integrated circuit package.

BACKGROUND ART

Relative small sized, but multi-functional and high performanceelectronic equipment such as personal computers (PCs), work stations,and other desktop type or desk-side type computers make use of highdensity integrated circuit packages. These become local sources of heat.Usually, heat-radiating fins are provided individually or in common forsuch high density integrated circuit packages. Use is made of naturalcooling by natural ventilation or forced cooling by common cooling finsfor the equipment as a whole so as to cool the same along with otherelements and units.

Some recent high integration LSI packages give off several watts ofheat. Further, along with the rise of the clock frequency used, theamount of heat generated increases. In particular, it is sometimes notpossible to obtain sufficient cooling with the above type of usual heatsink in the case of an LSI package generating from 5 to 6 or more wattsof heat. As the cooling fans for forced cooling, use is made of, forexample, 60 to 80 mm square sized fans for the above-mentioned desktoptype personal computers or 120 mm square sized fans for desk-side typecomputers, operated at a considerably high speed of, for example, 3000to 5000 rpm. Use of ones with more powerful cooling capacities is notpossible in view of the size of the equipment, costs, and noise.

That is, if the fans are made larger in size, the size of the equipmentincreases accompanying this, the costs increase, and the noise increasesas well, but the cooling capacity does not increase commensurate withthe same. Further, even if a number of fans are used arranged in seriesor in parallel, the size of the equipment and the costs increase inaccordance with this, but the resultant amount of cooling air does notsimilarly multiply. Further, operating the fan at a higher speed isdifficult in view of the noise. Also, even if a large sized fan isoperated at a low speed, the merits in terms of cooling effect and noisecommensurate with the demerits of the equipment size and costs cannot beobtained. For these reasons, as a result, it is not possible to supplysufficient cooling air for the heat sink of a high heat generating LSIpackage for example as mentioned above.

For example, a conventional example of the case of cooling a printedcircuit board mounted in high density mounting electronic equipment isshown in FIG. 1. In this conventional example, cooling fans 17 arearranged in a shelf 15 of the electronic equipment for cooling theprinted circuit boards 16, 16 . . . housed in the shelf 15. Whenheat-generating elements 1 are mounted on the printed circuit boards 16,16 . . . , it is necessary to increase the efficiency of cooling theheat-generating elements 1 by affixing known heat sinks provided with aplurality of heat-radiating fins to the heat-generating elements 1.

Note that in FIG. 1, 19 shows connectors for mounting the printedcircuit boards 16 to a back panel, while 20 shows an air duct.

The main object of a heat sink is to increase the heat conducting area.If trying to obtain a high heat radiating effect, the height of theheat-radiating fins must be made greater or the interval between theheat-radiating fins must be made narrower, but in an actual board, thiswould lead to a reduction in the mounting density and an increase in thefluid resistance and thus would cause the problem, it has been pointedout, of not being able to obtain the required performance.

Further, even with cooling by a cooling fan 17, it is not possible tocool just a specific heat-generating element 1 on a spot basis. When acertain air speed or more is already obtained, there is the problem thatthe demerit of the greater noise becomes greater than the improvement ofthe cooling efficiency due to the increased air speed.

In the known heat sink, when trying to improve the cooling capacity, itis necessary to increase the surface area of the heat-radiating fins.When narrowing the interval between heat-radiating fins to try toincrease the surface area, however, the pressure loss increases and theheat radiating effect is not effectively improved.

A conventional cooling device for cooling a heat-generating element isshown in FIG. 2. In this conventional device, a heat sink 2 formed of amaterial with a good heat conductivity, such as aluminum, is affixed asa heat radiator on the heat-generating element 1. The heat sink 2 isprovided on top with a plurality of comb-tooth-like heat-radiating fins4, 4 . . . . The heat emitted from the heat-generating element 1 isconducted to the heat sink 2, then absorbed by the cooling air.

That is, in a heat sink provided with such comb-tooth-likeheat-radiating fins, referring to FIG. 3, if the interval between theheat-radiating fins 4 is made narrower, the air speed V2 becomes smallerthan the air speed V1. Further, comparing the pressure loss of theheat-radiating fins 4 and the surrounding pressure loss, the surroundingpressure loss becomes far smaller so the majority of the cooling airends up flowing in the surrounding area.

Accordingly, if the amount of heat emitted by the heat-generatingelement 1 increases, it becomes necessary to raise the air speed nearthe heat-generating element 1 to raise the heat radiating effect andtherefore use of a more powerful fan becomes necessary.

On the other hand, to make the fan more powerful, in general the size ofthe fan is increased or else the rotational speed is raised. There isthe problem, however, that the result is an increase in the mountingspace of the fan or an increase in the noise.

To raise the heat radiating effect, it is also possible to increase thesurface area of the heat-radiating fins 4, but in this case there is theproblem that this causes an increase in the mounting space.

To resolve this, since the heat-generating elements or units emittingparticularly high heat in a piece of equipment are usually limited to ahandful of locations, it has been considered to provide theseheat-generating elements or units with heat sinks assembled with forexample individual small-sized cooling fans of about 25 to 40 mm squaresize so as to send the individually required amounts of cooling air tothe heat sinks of these heat-generating elements or units and performlocal forced cooling.

FIG. 4 gives front views, including partial cross-sections, illustratingschematically the kinds, that is, type, of mounting structures with sucha cooling fan and heat sink assembled together. Here, examples are shownof application to a cooling device of an LSI package. In the figure, 1is a package, that is, a heat-generating element, 2 is a heat sinkformed by a material with a good heat conductivity, and 3 is a coolingfan unit. Consideration may be given to a direct vertical mounting typewhere the fan unit 3 is mounted above the heat sink, as shown in FIG.4(A), and a buried mounting type where the fan unit 3 is buried in theheat sink 2, as shown in FIG. 4(B).

However, sufficient study has yet to be made of the shape, structure,etc. for meeting size requirements and achieving high coolingefficiencies for the realization of a heat sink provided with anindividual cooling fan for a heat-generating element or unit,particularly with equipment being made smaller in size and with highermounting densities. In particular, sufficient study has not been made ofa thin cooling structure able to meet the requirements of recent highdensity mounting equipment.

FIG. 5 gives a side view (A) and plan view (B) showing only the heatradiator portion in a cooling device of the mounting structure shown inFIG. 4(A). This heat radiator is comprised of a heat sink 2 formed of amaterial with a good heat conductivity and with a plurality ofheat-radiating fins 4, 4 . . . projecting out at the top surface and acooling fan unit 3 provided above the heat sink 2.

In such a conventional heat radiator comprised of a heat sink andcooling fan formed integrally together, the cooling fan unit 3 isconstructed to be driven by a centrally disposed motor 3c to turn itsfan blades 3. The motor 3c does not necessarily have to have a highcooling air generating capacity, since the area of projection of thecooling air on the blowing surface is large. To exhibit the desiredcooling effect, it is necessary to raise the rotational speed etc. ofthe motor 3c. This has the problem of causing the generation of noiseetc.

Further, the cooling fan unit 3, as mentioned above, has a motor 3disposed at its center, so there was the problem that the amount ofcooling air becomes smaller at the center of the heat sink 2 where theamount of heat generated is the greatest and so the cooling efficiencyis not by any means high.

FIG. 6 gives a side view (A) and a plan view (B) for explaining thecooling action in the heat radiator of the above-mentioned construction.This heat radiator is comprised of a heat sink 2 which has a pluralityof pin-shaped heat-radiating fins 4, 4 . . . projecting out from its topsurface and which is adhered or affixed to the heat-generating element 1and a cooling fan unit 3 which has a fan 3b accommodated in a casing 3aand which is mounted above the heat sink 2. It is designed so that thefan 3b of the cooling fan unit 3 is operated to cool the heat sink 2 towhich the heat emitted from the heat-generating element 1 is conducted.

In the above-mentioned conventional example, however, the distancebetween the bottom end of the fan 3b and the top surface of the heatsink 2 was substantially zero, so there was the problem that the areadirectly under the fan motor unit, that is, the center portion of theheat sink 2, became a dead zone, inviting a reduction of the coolingefficiency and resulting in a larger pressure loss and thus thereduction of the capacity of the fan 3b.

Further, for example, in the case of the so-called push system where theexhaust air of the fan 3b is blown against the heat sink 2, the flow ofair diffuses while swiveling as shown by the arrow marks in FIG. 6(B),so there is the problem that mutual interference is caused, dead pointsoccur, and therefore the effective amount of air contributing to theactual cooling is reduced.

Also, to resolve these problems and improve the cooling efficiency, itis possible to use a high speed fan for the cooling unit 3, but in thiscase there is the problem that the noise ends up becoming greater.

DISCLOSURE OF THE INVENTION

The present invention was made so as to resolve the above problems andhas as its object the provision of a heat-generating element coolingdevice which can effectively cool a specific heat-generating element.

Further, the present invention has as its object the provision of aheat-generating element cooling device which supplies cooling air fromthe center portion and therefore enables the pressure loss circuit to bearranged not in parallel, but in series and enables the distance overwhich the cooling air passes to be more than halved and the pressureloss to be decreased.

Next, the present invention has as its object the provision of anintegral fan type heat-generating element cooling device, that is, aheat sink system provided integrally with a fan for cooling theheat-generating element or heat-generating unit which improves thecooling efficiency and has a shape and structure enabling high densitymounting.

Still further, the present invention has as its object the provision ofan integral fan type heat-generating element cooling device whichenables effective cooling of a heat-generating element withoutinhibiting the mounting efficiency.

A more specific object of the present invention is to provide aheat-generating element cooling device having a fan constructionenabling uniform heat radiation.

Another more specific object of the present invention is to provide aheat-generating element cooling device having a heat sink structurewhich enables uniform heat radiation.

Still another more specific object of the present invention is toprovide a heat-generating element cooling device having a fanconstruction which enables the size to be made thin.

Still another more specific object of the present invention is toprovide a heat-generating element cooling device having an alignedconstruction of the heat sink and fan which enables the size to be madethin.

To achieve the above-mentioned objects, the heat-generating elementcooling device according to the present invention has a heat radiatorattached to a heat-generating element and a blowing device for blowingcooling air to the heat radiator, the heat radiator being comprised of aheat sink formed of a material with a good heat conductivity andprovided with a plurality of heat-radiating fins and a hollow pipeportion arranged at the center portion of the heat sink, wherein coolingair is forcibly introduced from the blowing device to the pipe portion,then is ejected from small blowing holes formed in the pipe portion.

In this construction, the cooling air blown out from the blowing devicemay be distributed to a plurality of heat radiators through an airconduit passage and that air conduit passage may be connected to aplurality of air conduit pipes through a coupling portion. In this way,by suitably selecting and connecting the air conduit pipes, it becomespossible to cancel out the differences in disposition of theheat-generating elements on the printed circuit board and becomespossible to apply the device to various types of printed circuit boards.

Further, the air conduit passage may be connected to a blowing devicethrough a coupling portion provided on a front board of the printedcircuit boards to enable connection to a plurality of printed circuitboards.

Further, the cooling air from the cooling device is guided from the pipeportion on the center line of the heat-generating element. The pipeportion has small blowing holes in the bottom wall. The cooling airtherefore concentratedly cools the area near the center line of the heatsink, which is the high temperature area, to improve the overall coolingefficiency. Further, the cooling air is guided to symmetrical positionswith respect to the center line of the heat-generating element by thepipe portion, so concentratedly cools the area near the center line ofthe heat sink, which is where the high temperature area is located, andthereby improves the overall cooling efficiency.

Still further, the cooling air is guided to the center of the heat sinkby a guide portion and concentratedly cools the center portion where thehigh temperature area is so as to improve the overall coolingefficiency. Also, the small blowing holes are formed in the center ofthe bottom wall of the guide portion, so the cooling air is ejected tothe center portion of the heat sink without mutual interference.

Also, to achieve the above-mentioned objects, the heat-generatingelement cooling device according to the present invention has a heatsink with a plurality of heat-radiating fins projecting from its topsurface and a cooling fan unit attached to the heat sink, the surface ofthe heat sink having provided on it a partition plate which passesthrough the center and radially sections off the surface portion of theheat sink. Here, the cooling fan unit may be disposed a suitabledistance from the top surface of the heat sink and the clearance betweenthe heat sink and the cooling fan unit may be covered by an enclosingwall.

In this construction, the partition plate prevents mutual interferencein the cooling air from the cooling fan unit, promotes the quick flowout from the heat sink, and prevents the reduction of the coolingefficiency due to the interference of the cooling air. Further, an airgap is formed between the cooling fan unit and the heat sink, so thecooling air blown out from the cooling fan unit travels over not onlythe peripheral edge portions, but substantially evenly over the centerportion of the heat sink as well and therefore enables a high overallcooling efficiency to be exhibited.

Further, to attain the above-mentioned objects, the heat-generatingelement cooling device according to the present invention is constructedso that the heat-radiating fins of the heat sink become smaller insectional area the further toward the front end, by which it becomeseasier for the cooling air blown out from the cooling fan to reach thebase surface of the heat-radiating fins of the heat sink. As a result,the effective amount of air is increased in the case of use of a coolingfan with the same amount of blowing.

The heat-radiating fins occupy every other intersection of a matrix-likegrid and are arranged in a staggered manner. By intermittently providingthe heat-radiating fins, the pressure loss of the cooling air is reducedand the effective amount of air is increased and, further, the coolingair can more easily strike all of the heat-radiating fins. In this way,according to the present invention, the reduction of the pressure lossof the cooling air is held to the minimum and the heat radiating surfacecan be increased as well.

Also, to achieve the above-mentioned objects, according to theheat-generating element cooling device of the present invention,provision is made of an integral fan type heat-generating elementcooling device of the direct vertical mounting type provided with a heatsink disposed on the top surface of the heat-generating element andhaving a plurality of heat-radiating fins and a cooling fan unitarranged above the heat sink and having a motor portion operating at itscenter, wherein at least one auxiliary blade is provided at the bottomsurface of the motor portion of the fan unit.

Since the integral fan type heat-generating element cooling deviceaccording to the present invention is comprised in this way, in a directvertical mounting type where the fan unit is mounted above the heatsink, it is possible to use the auxiliary blades provided below themotor portion of the fan unit to agitate the air below the fan unit andtherefore eliminate any dead zones occurring just beneath the fan unit.

Further, to achieve the above-mentioned objects, the heat-generatingelement cooling device according to the present invention has a heatsink provided with a plurality of pin-shaped heat-radiating fins and acooling fan unit affixed above the heat sink, the base surface of theheat-radiating fins of the heat sink having at least partially aninclined surface formed so as to become lower the further toward thecenter.

As a result, the height of projection of the adjoining heat-radiatingfins from the heat-radiating fin base surface is higher in the onepositioned inward on the heat sink and therefore a difference is causedin the pressure loss between the two. Due to this difference in thepressure loss, the cooling air blown from the cooling fan unit collectsat the center portion of the heat sink, so the center portion of theheat sink, where the heat emission is high, is efficiently cooled. Inaddition, the thickness of the heat sink is less at the center portion,so the heat radiation is promoted. Further, the thickness becomesgreater the further toward the outer circumference, so the heatconductivity is improved and the conductive cooling effect is improved.

In the same way, provision is made of an integral fan typeheat-generating element cooling device of the direct vertical mountingtype where the heat sink is formed at least partially with a basesurface inclined so as to include an inclination which descends towardthe center portion, wherein a heat pipe is laid so as to extend alongthe inclined base surface from the peripheral portions to the centerportion. According to this, by laying the heat pipe on the base surfaceof the heat sink inclined toward the center portion, the heat emitted atthe center portion of the heat-generating element is conducted to theouter peripheral portions to increase the amount of heat radiation andfurther raise the cooling efficiency.

Further, to achieve the above-mentioned objects, the heat-generatingelement cooling device according to the present invention has a covermember arranged a suitable distance away from the top surface of aheat-generating element mounted on a printed circuit board and ofsubstantially the same area as the heat-generating element and one ormore fan units, the fan units being used to blow cooling air in theclearance between the cover member and surface of the heat-generatingelement so as to cool the heat-generating element.

Further, the heat-generating element cooling device according to thepresent invention has a heat sink affixed to the top surface of theheat-generating element and provided with a plurality of heat-radiatingfins on its top surface and fan units affixed above the heat sink, thefan units being provided at symmetrical positions with respect to thecenter of the heat sink and the individual fan units being driven sothat the directions of blowing face the center of the heat-generatingelement.

Further, it may be constructed to have a heat sink affixed on theprinted circuit board adjoining the heat-generating element and providedwith a plurality of heat-radiating fins at the top surface and a fanunit affixed above the heat sink, the heat sink and the heat-generatingelement being connected through a heat pipe.

According to this construction, a cover member is disposed above theheat-generating element and cooling air is blown from the fan unittoward the clearance. The cooling air is ejected toward the top surfaceof the heat-generating element to cool the heat-generating element,while the cooling air reflected back by the heat-generating element isagain reflected back from the cover member to reach the heat-generatingelement, thereby contributing to the cooling of the heat-generatingelement.

Further, the fan unit is attached detachably to the cover member, so canbe replaced if defective or if breaking down.

Also, the fan unit is attached at a position with the fan rotationalshaft offset from the center of the heat-generating element. As aresult, the cooling air from the fan is directly blown against thecenter portion of the heat-generating element, that is, the high heatemitting region of the heat-generating element, and the coolingefficiency is improved.

Further, the cover member is formed by a material with a good heatconductivity and a spring member with a good heat conductivity isinterposed between the cover member and the surface of theheat-generating element. As a result, part of the heat from theheat-generating element is conducted to the cover member through thespring member, so the cooling efficiency is improved.

Further, the cover member is formed with a plurality of ridgesprojecting out to the clearance side. These ridges give a throttlingeffect to the cooling air passing inside the clearance and raise the airspeed. Also, they direct the cooling air to the surface portion of theheat-generating element so as to improve the cooling efficiency.

A plurality of fan units affixed above the heat sink are provided atsymmetrical positions with respect to the center of the heat sink.Further, the individual fan units are driven so that their blowingdirections face the center of the heat-generating element. As a result,the cooling air from the individual fan units passes through the centerof the heat-generating element, that is, the high heat emitting portion,and the cooling efficiency is improved.

Further, according to another construction, the heat sink is mountedadjoining the heat-generating element and with a fan unit mounted to thetop surface. The heat sink and the heat-generating element are connectedby a heat pipe and the heat emitted by the heat-generating element isconducted to the heat sink through the heat pipe.

Also, to achieve the above-mentioned objects, the heat-generatingelement cooling device according to the present invention provides aburied mounting type heat-generating element cooling device providedwith a heat sink disposed on the top surface of a heat-generatingelement and having a plurality of heat-radiating fins disposed at leastexcept at a center portion of the same, a cover having an air intake andexhaust opening facing the center portion of the heat sink and attachedso as to cover the top surface of the heat sink, and a cooling fan unitinside the air intake and exhaust opening of the cover and buried in thecenter portion of the heat sink, wherein the circuit components fordriving the fan unit are attached to the inner surface of the cover orthe inner surface of the heat sink.

Further, in this construction, since the circuit components for controlof the rotation of the fan unit are attached at the inside surface ofthe heat sink or the cover, not provided above or below the motor, thecooling device can be made thinner by that amount of space or the fanmotor can be made longer laterally and the diameter made smaller so asto reduce the overall size of the cooling device.

Also, to achieve the above-mentioned objects, the heat-generatingelement cooling device according to the present invention is comprisedof a heat sink disposed on the top surface of a heat-generating elementmounted on a printed circuit board and having a base surface, a coolingair throttling mechanism supported by the base surface, and a pluralityof heat-radiating fins disposed on the base surface around the throttlemechanism, a plate-shaped cover covering the top surface of the heatsink and having an air intake and exhaust opening formed at a positionfacing the throttling mechanism, and a cooling fan unit positionedbeneath the air intake and exhaust opening of the cover and mounted soas to be accommodated in the throttling mechanism.

Further, provision is further made of a male screw member of a materialwith a good heat conductivity affixed near the center portion of the topsurface of the heat-generating element and, in the heat sink, the fanmounting portion is formed at a position offset from the center portionand a female screw portion engaging with the male screw member is formednear the center portion.

In an integral fan type heat-generating element cooling device of theburied mounting type according to such a construction, it is possible touse the throttling mechanism formed in the heat sink for heat radiation.Further, by joining the heat sink with the buried fan unit and theheat-generating element by a screw, by making the male screw affixed tothe heat-generating element one with a large heat conductivity, and bymaking the female screw provided in the heat sink one which contacts thecooling air, it is possible to make a highly reliable joiningconstruction and also contribute to the improvement of the coolingefficiency.

Further, to achieve the above-mentioned objects, the heat-generatingelement cooling device according to the present invention provides anintegral fan type heat-generating element cooling device of the buriedmounting type provided with a heat sink disposed at the top surface of aheat-generating element and having a plurality of heat-radiating finsdisposed on the base surface except at least at a fan mounting portion,a cover having an air intake and exhaust opening at a position facingthe fan mounting portion and attached so as to cover the top surface ofthe heat sink, and a cooling fan unit attached so as to be buried in thefan mounting portion positioned beneath the air intake and exhaustopening of the cover, wherein the side of the cover has formed anextension portion extending directly above and outward of theheat-generating element and a shielding plate connected to the edge ofthe extension portion and extending downward.

In this construction, the shielding plate provided at the extensionportion of the cover is used to eliminate interference of the exhaustair between parallel disposed cooling devices and the exhaust air isintroduced to the bottom surface of the heat-generating element so as toimprove the cooling efficiency.

Further, to achieve the above-mentioned objects, according to theheat-generating element cooling device according to the presentinvention, there is provided an integral fan type heat-generatingelement cooling device of the side mounting type, wherein provision ismade of a heat sink disposed on the top surface of the heat-generatingelement mounted on a board and having a plurality of heat-radiatingfins, a cover affixed so as to cover the top surface of the heat sinkand having an extension portion extending to the side of the heat sink,and a fan unit mounted beneath the extension portion of the cover, theoperation of the fan unit causing the cooling air to be concentratedlyand effectively led to the heat sink between the cover and theheat-generating element.

Still further, in the side mounting type where the fan unit is disposedat the side of the assembly of the heat-generating element and the heatsink, by making the construction a closed one where the cooling air canbe effectively led to the heat sink and further by disposing a memberfor effectively guiding the cooling air inside to the heat emittingportion, it is possible to form the cooling device thin and further toraise the cooling efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a conventional example of the case of cooling aprinted circuit board.

FIG. 2 is a view of the problems in the conventional coolingconstruction.

FIG. 3 is a view explaining the action of the conventional heat sink.

FIGS. 4(A) and 4(B) are frontal views including partial cross-sectionsillustrating schematically the types of mounting structures ofcombinations of cooling fans and heat sinks.

FIGS. 5(A) and 5(B) are views showing a conventional example of the typeof FIG. 5(A), wherein (A) is a side view and 5(B) is a plan view of theheat sink.

FIGS. 6(A) and 6(B) views showing a conventional example of the type ofFIG. 4(B), wherein (A) is a side view and (B) is a plan view of the heatsink.

FIGS. 7(A) and 7(B) are views of the construction of a piece ofelectronic equipment to which a first embodiment of the heat-generatingelement cooling device according to the present invention is applied,wherein 7(A) is an overall view and 7(B) is an enlarged view ofimportant portions.

FIG. 8 is a perspective view of the construction of a heat radiator inthe first embodiment of the heat-generating element cooling deviceaccording to the present invention.

FIG. 9 is a plan view of FIG. 8.

FIGS. 10(A) and 10(B) are views of a modification of FIG. 8, wherein10(A) is a perspective view and 10(B) is a plan view.

FIG. 11 is a cross-sectional view of the construction of a heat radiatorin a second embodiment of a heat-generating element cooling deviceaccording to the present invention.

FIG. 12 is a cross-sectional view of a modification of FIG. 11.

FIG. 13 is a cross-sectional view of another modification of FIG. 11.

FIGS. 14(A) and 14(B) are views of the construction of a heat radiatorin a third embodiment of the heat-generating element cooling deviceaccording to the present invention, wherein 14(A) is a plan view and14(B) is a sectional view along the line B--B.

FIG. 15 is a perspective view of the construction of a heat radiator ina fourth embodiment of the heat-generating element cooling deviceaccording to the present invention.

FIG. 16 is a cross-sectional view of FIG. 15.

FIG. 17 is a plan view of FIG. 16.

FIG. 18 is a cross-sectional view of a modification of FIG. 15.

FIG. 19 is a view of a plan view of FIG. 18.

FIG. 20 is a view of the construction of a piece of electronic equipmentto which a fifth embodiment of the heat-generating element coolingdevice according to the present invention is applied.

FIG. 21 is an enlarged view of important portions of FIG. 20.

FIGS. 22(A) and 22(B) are views of the state of connection of airconduit pipes.

FIGS. 23(A) and 23(B) are view of a sixth embodiment of theheat-generating element cooling device according to the presentinvention, wherein 23(A) is a cross-sectional view and 23(B) is a planview of the heat sink of the same.

FIGS. 24(A) and 24(B) are view of a seventh embodiment of theheat-generating element cooling device according to the presentinvention, wherein 24(A) is a cross-sectional view and 24(B) is a planview of the heat sink of the same.

FIGS. 25(A) and 25(B) are view of a eighth embodiment of theheat-generating element cooling device according to the presentinvention, wherein 25(A) is a cross-sectional view and 25(B) is a planview of the heat sink of the same.

FIGS. 26(A) and 26(B) are view of an ninth embodiment of theheat-generating element cooling device according to the presentinvention, wherein 26(A) is a cross-sectional view and 26(B) is a planview of the heat sink of the same.

FIG. 27 is a view of a modification of FIG. 26.

FIGS. 28(A) and 28(B) are a front cross-sectional view 28(A) and a topview 28(B) of the construction of a 10th embodiment of theheat-generating element cooling device according to the presentinvention.

FIG. 29 is an enlarged cross-sectional view of the center portion of thefront cross-sectional view of the cooling construction of FIG. 28.

FIGS. 30(A) to 30(C) are bottom views illustrating various shapes ofauxiliary blades.

FIGS. 31(A) to 31(C) are views of a 11th embodiment of theheat-generating element cooling device according to the presentinvention, wherein 31(A) is a cross-sectional view, 31(B) is a sidesectional view, and 31(C) is a plan view.

FIGS. 32(A) and 32(B) are plan views of two modifications of FIG. 31.

FIGS. 33, 33(A) and 33(B) are a top view, front view, and side view ofthe construction of an 12th embodiment of the heat-generating elementcooling device according to the present invention.

FIG. 34 is a front cross-sectional view along the section A--A of FIG.33.

FIGS. 35, 35(A) and 35(B) are a top view, front view, and side view of amodification of the embodiment of FIG. 33.

FIG. 36 is a perspective view of a 13th embodiment of theheat-generating element cooling device according to the presentinvention.

FIGS. 37(A) and 37(B) are views showing details of FIG. 36, wherein37(A) is a plan view and 37(B) is a side view.

FIGS. 38(A) and 38(B) are views of a 14th embodiment of aheat-generating element cooling device according to the presentinvention, wherein 38(A) is a plan view and 38(B) is a side view.

FIGS. 39(A) to 39(C) are views of a 15th embodiment of theheat-generating element cooling device according to the presentinvention, wherein 39(A) is a plan view, 39(B) is a side view, and 39(C)is an enlarged view of the C portion of 39(B).

FIGS. 40(A) and 40(B) are views of a 16th embodiment of theheat-generating element cooling device according to the presentinvention, wherein 40(A) is a plan view and 40(B) is a side view.

FIG. 41 is a plan view of the heat sink in the embodiment of FIG. 40.

FIGS. 42(A) and 42(B) are views of a modification of FIG. 40, wherein42(A) is a plan view and 42(B) is a plan view of the heat sink.

FIGS. 43(A) and 43(B) are views of another modification of FIG. 40,wherein 43(A) is a plan view and 43(B) is a plan view of the heat sink.

FIGS. 44(A) and 44(B) are views of a 17th embodiment of theheat-generating element cooling device according to the presentinvention, wherein 44(A) is a side view and 44(B) is a plan view.

FIG. 45 is a disassembled perspective view of FIG. 44.

FIGS. 46(A) and 46(B) are views explaining the action of the embodimentof FIG. 44.

FIGS. 47(A) and 47(B) are views explaining the method of affixing theheat pipes, wherein 47(A) is a disassembled view and 47(B) is a sideview of the assembled state.

FIG. 48 is a view explaining a modification of FIG. 47.

FIG. 49 is a view of an affixing fitting.

FIGS. 50(A) and 50(B) are views of a modification of FIG. 44, wherein50(A) is a side view and 50(B) is a plan view.

FIGS. 51, 51(A) and 51(B) are a top view, front view, and side view ofthe construction of a heat-generating element cooling device of the typeof FIG. 4(B).

FIGS. 52(A) and 52(B) are partial enlarged cross-sectional views of thecenter portion in the section along the section A--A in FIG. 51.

FIGS. 53 gives a top view, front view, and side view of the constructionof a 18th embodiment of the heat-generating element cooling deviceaccording to the present invention.

FIGS. 54(A) and 54(B) are partial enlarged cross-sectional views of thecenter portion in the section along the section A--A in FIG. 53.

FIGS. 55, 55(A) and 55(B) are a top view, front view, and side view ofthe construction of a modification of the embodiment of FIG. 53.

FIGS. 56(A) and 56(B) are partial enlarged cross-sectional views of thecenter portion in the section along the section A--A in FIG. 55.

FIGS. 57(A), 57(A)-1, 57(B) and 57(B)-1 are a top view and front view ofthe construction of a first example overall (A) and cover (B) of aconventional integral fan type heat-generating element cooling device ofthe type of FIG. 4(B).

FIGS. 58(A), 58(A)-1, 58(B) and 58(B)-1 are a top view and front view ofthe construction of a second example overall (A) and cover (B) of aconventional integral fan type heat-generating element cooling device ofthe type of FIG. 4(B).

FIGS. 59(A), 59(A)-1, 59(B) and 59(B)-1 are a top view and front view ofthe construction of the 19th embodiment overall (A) and cover (B) of theheat-generating element cooling device according to the presentinvention.

FIGS. 60 and 60(A) are a top view and front view of the construction ofjust the heat sink in the embodiment of FIG. 59.

FIG. 61 is an enlarged perspective view of the construction of thethrottling mechanism portion.

FIGS. 62 and 62(A) are a top view and front view of the construction ofa 20th embodiment of the heat-generating element cooling deviceaccording to the present invention.

FIGS. 63 and 63(A) are a top view and front view of the construction ofan example of a male screw member.

FIGS. 64(A) to 64(C) are cross-sectional views of the section A--A ofFIG. 63 for showing various examples of the construction of male screwmembers.

FIG. 65 is a perspective view of the mounting state in the case ofmounting a plurality of conventional integrated fan type heat-generatingelement cooling devices of the type of FIG. 4(B) in parallel.

FIG. 66 is a top view of FIG. 65.

FIGS. 67, 67(A) and 67(B) are a top view, front view, and side view ofthe construction of a 21st embodiment of a heat-generating elementcooling device according to the present invention.

FIG. 68 is a perspective view of the mounting state in the case ofmounting a plurality of the embodiments of FIG. 67 in parallel.

FIG. 69 is a top view of FIG. 68.

FIGS. 70(A) and 70(B) are a top view (A) and a front cross-sectionalview (B) of the construction of a 22nd embodiment of the heat-generatingelement cooling device according to the present invention.

FIG. 71 is a perspective view of the construction of the embodiment ofFIG. 70.

FIG. 72 is a top view of the construction of a first modified embodimentof the embodiment shown in FIG. 70.

FIG. 73 is a perspective view of the construction of the first modifiedembodiment of FIG. 72.

FIG. 74 is a perspective view of the construction of a second modifiedembodiment of the embodiment shown in FIG. 70.

FIGS. 75(A) and 75(B) are a top view (A) and a front cross-sectionalview (B) of the construction of a third modified embodiment of theembodiment shown in FIG. 70.

FIGS. 76(A) and 76(B) are a top view (A) and a front cross-sectionalview (B) of the construction of a fourth modified embodiment of theembodiment shown in FIG. 70.

FIG. 77 is a partially enlarged view of the B portion of FIG. 76.

FIGS. 78(A) and 78(B) are a top view (A) and a front cross-sectionalview (B) of the construction of a fifth modified embodiment of theembodiment shown in FIG. 70.

FIG. 79 is a perspective view of the modified embodiment of FIG. 78.

FIG. 80 to FIG. 82 give top views and front views of examples of thearrangement and shape of heat-radiating fins of the heat sink in theembodiment shown in FIG. 70.

BEST MODE FOR CARRYING OUT THE INVENTION

Below, the preferred embodiments of the cooling device according to thepresent invention will be explained in detail based on the attacheddrawings.

First, the construction of FIG. 7 shows the construction of a piece ofelectronic equipment to which the first embodiment of theheat-generating element cooling device according to the presentinvention is applied, in particular, the construction of the shelf 15 ofthe same. (A) is an overall view and (B) is an enlarged view ofimportant portions of the same. In a piece of equipment of thisconstruction, in the shelf 15, a plurality of printed circuit boards 16,16 . . . are plugged in to a rear back panel for connection.

On the printed circuit boards 16, 16 . . . are mounted various types ofelectronic devices including heat-generating elements 1. To introducecooling air for cooling these elements into the shelf 15, the shelf 15has cooling fans 17. Note that in FIG. 7, 20 shows an air duct providedfor uniformly cooling the inside of the shelf 15. The flow of thecooling air inside the shelf 15, that is, the air flow, is shown by thearrow marks in FIG. 7.

Further, to cool a heat-generating element 1 on a spot basis, a blowingdevice 5 is mounted at the bottom of the shelf 15. The cooling air fromthis blowing device 5 is sent through a bellows-type duct 21 to a heatradiator 10, which serves as the main part of the heat-generatingelement cooling device of the present embodiment.

Details of the heat radiator 10 in the heat-generating element coolingdevice of the present embodiment are shown in FIG. 8 and FIG. 9. Theheat radiator 10 according to this embodiment is comprised of a heatsink 2 formed by a material with a good heat conductivity, for example,aluminum, and a pipe portion 6 disposed at the center portion of theheat sink 2. The entire top surface of the heat sink 2 except for thecenter portion has a plurality of pin-shaped heat-radiating fins 4, 4 .. . projected out from it.

The pipe portion 6 is formed having a hollow rectangular cross-sectionand is sealed at its end portion. Further, the side walls of the pipeportion 6 have a plurality of small blowing holes 7, 7 . . . formed inthem corresponding to the intervals of the heat-radiating fins 4.

On the other hand, as shown in FIG. 7, the blowing device 5 ispreferably one provided with a high static pressure characteristic, suchas a sirocco fan, a blower, or a compressor. In the illustratedembodiment, use is made of a sirocco fan. The exhaust port of theblowing device 5 has connected to it the bellows-type duct 21communicating with the air duct. Cooling air is blown to the pipeportion 6 of the heat radiator 10 through this bellows-type duct 21.

Accordingly, in this embodiment, the cooling air blown through theserpentine duct 21 to the pipe portion 6, as shown by the arrow marks inFIG. 9, is ejected from the small blowing holes 7 to the sides of thepipe portion 6 and cools the heat-radiating fins 5 disposed at the sidesof the pipe portion 6.

Note that the heat sink 2 of the heat radiator 10 according to thepresent embodiment is provided with pin-shaped heat-radiating fins 4,but in place of this it is also possible to form a plurality ofwall-shaped heat-radiating fins 4 as shown in FIG. 10. In this case, theheat-radiating fins 4 are arranged along the opening direction of thesmall blowing holes 7 of the pipe portion 6 (see FIG. 10(B)).

Further, in these embodiments, the pipe portion 6 of the heat radiator10 may be formed integrally with the heat sink 2, but it is alsopossible to form the pipe portion 6 separately and to attach itdetachably to the heat sink 2. In this case, the pipe portion 6 may beconstituted so as to be mounted engaged with the heat sink 2.

FIG. 11 shows the heat radiator 10 of a second embodiment of aheat-generating element cooling device according to the presentinvention. In the heat radiator 10 according to this embodiment, theheat sink 2 has mounted to it a cover member 22. A pipe portion 6 isformed between a pair of suspended walls 22a, 22a, which are suspendedfrom the center portion of the cover member 22 and which have aplurality of small blowing holes 7, 7 . . . pierced through them, andthe heat sink 2.

The depth direction of the pipe portion 6 formed between the suspendedwalls 22a and the heat sink 2 is closed by a closing wall 22b formed atthe cover member 22 or constituting part of the same. Further, the covermember 22 according to this embodiment is provided with engaging walls23 at the side wall portions which for example are engaged withengagement grooves 18 made in the heat sink 2.

FIG. 12 shows a modification of FIG. 11. The pipe portion 6 in thismodification is disposed at a suitable height from the base surface 12of the heat-radiating fins 4. A plurality of small blowing holes 7, 7 .. . are made through the bottom wall 13 and the side walls of the pipeportion 6.

Accordingly, in this embodiment, the cooling air is ejected from thecenter toward the sides and is ejected also to the top of the centerline L (see FIG. 9) of the heat sink 2 so the center portion of theheat-generating element 1, i.e., the high temperature area, iseffectively cooled.

FIG. 13 shows another modification of FIG. 11. The pipe portion 6 inthis modification has a circular section. Small blowing holes 7 are madein the bottom side of the pipe portion 6.

Accordingly, in the heat radiator according to this embodiment, as shownby the arrow marks in the figure, the cooling air is ejected from thepipe portion 6 at a downward slant and so like with the abovemodification, the center portion of the heat-generating element 1, i.e.,the high temperature area, is effectively cooled.

FIG. 14 shows the heat radiator 10 in a third embodiment of theheat-generating element cooling device according to the presentinvention, wherein (A) is a plan view and (B) is a sectional view alongthe line B--B. In the embodiment, two pipe portions 6 are provided atsymmetrical positions with respect to the center line L of the heat sink2. Small blowing holes 7 are made in the bottom walls 13 of these pipeportions 6. Therefore, in this embodiment, the cooling air is ejectedfrom the two pipe portions 6 toward the center line L of the heat sink2, and the center portion, that is, the high temperature area, iseffectively cooled.

FIG. 15 is a perspective view of the heat radiator 10 in a fourthembodiment of the heat-generating element cooling device according tothe present invention. FIG. 16 is a cross-sectional view of the same,and FIG. 17 is a plan view thereof. The pipe portion 6 in thisembodiment has a guide portion 14 which bends toward the center portionof the heat sink 2. The front end of this guide portion 14 is opened. Inthe state attached to the heat sink 2, it abuts against the base surface12 of the heat-radiating fins of the heat sink 2 and therefore is closed(see FIG. 16). Therefore, in this embodiment, the cooling air is guidedto the center portion of the heat sink 2 to cool the center portion ofthe heat sink 2 and also is ejected from the small blowing holes 7 madein the side walls of the guide portion 14 toward the sides to cool thesurrounding heat-radiating fins 4,4 . . . (see FIG. 17).

A modification of the heat radiator shown in FIG. 15 is shown in FIG.18. FIG. 19 is a plan view of the same. The guide portion 14 in thismodification is formed with a bottom. Small blowing holes 7 are made inthe center of the bottom wall 13 of the guide portion 14 disposed at asuitable height position from the base surface 12 of the heat-radiatingfins 4 of the heat sink 2. Accordingly, in this modification, thecooling air is ejected to the center of the heat sink 2, a hightemperature area, in a state with no interference, to enable a greaterimprovement of the cooling efficiency (see FIG. 18 and FIG. 19).

FIG. 20 shows the construction of a piece of electronic equipment towhich a fifth embodiment of the heat-generating element cooling deviceaccording to the present invention is applied. In equipment of thisconstruction, modules M, M . . . in which the heat-generating elements 1are mounted are attached on the printed circuit boards 16, 16 . . .provided with front plates 16a at the side edges corresponding to theopen face of the shelf 15. The heat-generating elements 1 of the modulesM have heat radiators 10 attached to them. Cooling air is blown to theheat radiators 10 by connecting an air conduit passage 11 to the pipeportions 6 of the heat radiators 10. Further, the air conduit passage 11and the blowing device 5 are connected by a coupling portion 8' providedat the front plates 16a of the printed circuit boards 16.

The blowing device 5, as shown in FIG. 21, is provided with a blower ora pump or other blowing device 24 and a throttle valve 25. The throttlevalve 25 is adjusted based on information from the temperature sensors26, 26 . . . disposed near the heat radiators 10, enabling a supply ofcooling air to the heat radiators 10 controlled in accordance with thestate of heat emission.

Note that in FIG. 21, reference 29 shows a valve controller whichadjusts the throttle valve 25 by comparing the information from thetemperature sensors 26 and the setting. Further, two or more blowingdevices 24 may be disposed so that when the detection value of apressure sensor 27 or a flow sensor 27 disposed at the output side fallsbelow a lower limit setting, a standby device may be operated andthereby the redundancy improved. Also, in FIG. 21, 28 is a selectivecontroller for selecting the blowing devices 24 by comparing informationfrom the pressure sensors etc. 27 and the settings, and 30 is a switcheroperating by a signal from the selective controller 28.

On the other hand, the air conduit passage 11 is formed by suitablyconnecting a plurality of air conduit pipes 9, 9 . . . . The air conduitpipes 9 are comprised of a main pipe portion 9a and a branched pipeportion 9b branched from the same and have a substantially L-shaped plansection. As shown in FIG. 22(A), a joint portion 8 is formed at one endof the main pipe portion 9a. The other end of the main pipe portion 9aof another air conduit pipe 9 is fit into this or is connected byscrewing. The branch pipe portion 9b is connected to the pipe portion 6of the heat radiator 10.

Note that in FIG. 22, 8a shows an O-ring attached to the couplingportion 8. Further, as mentioned above, the end of the air conduitpassage 11 formed connecting the plurality of air conduit pipes 9, asshown in FIG. 22(B), may be closed by a cap member 9c.

Further, the above-mentioned air conduit pipes 9 may be prepared inadvance in numerous types with different lengths of the main pipeportions 9a and branched pipe portions 9b and be suitably selected andused in accordance with the disposition of the high heat-generatingelements 1 on the printed circuit boards 16, 16 . . . .

As clear from the above explanation of the embodiments, according to theheat-generating element cooling device of the present invention, it ispossible to cool a specific element with a high cooling efficiency.

FIG. 23 shows a sixth embodiment of the heat-generating element coolingdevice according to the present invention, especially an integral fantype heat-generating element cooling device. The heat-generating elementcooling device 10 of the embodiment has an integral construction of afan of the direct vertical mounting type and heat sink as shown in FIG.4(A) and is comprised of a heat sink 2 formed by a material with a goodheat conductivity such as an aluminum material and a cooling fan unit 3.

On the top surface of the heat sink 2 is provided a partition plate 31with a cross planar shape with the intersection portion 31a positionedat the center of the heat sink 2. In each region sectioned off by thepartition plate 31 are provided a plurality of pin-shaped heat-radiatingfins 4, 4 . . . at equal pitches. By this, the heat radiating portion ofthe heat sink 2 is sectioned off radially. This partition plate 31 isprovided so that the cooling air blown out from the later mentionedcooling fan unit 3 will not strike the base end of the heat-radiatingfins 4, that is, the base surface 12 of the heat sink 2 to interferewith other flows and thereby reduce the cooling efficiency, but isprovided at a suitable height from the base surface of the heat sink 2.

On the other hand, the cooling fan unit 3 is formed with a fan 3baccommodated in a casing 3a. For example, in the case of the pushsystem, as shown by the arrow marks in FIG. 23(A), the surrounding airis sucked in from above and forcibly exhausted to the heat sink 2 side.This cooling fan unit 3 is affixed to the heat sink 2 through anenclosing wall 33 comprised of a cylinder. A clearance 32 of suitabledimensions is formed at the bottom edge, more specifically, between thebottom end of the fan 3b and the top end surface of the heat sink 2.

Accordingly, in this embodiment, the cooling air forcibly blown from thecooling fan unit 3 is sent through the clearance 32 surrounded by theenclosing wall 33 to the heat-radiating fins 4, 4 . . . of the heat sink2 and cools the heat sink 2 absorbing the heat emitted by theheat-generating element 1. The cooling air passing through the clearance32 reaches not only near the outer circumference of rotation of the fan3b by the action of the clearance 32, but diffuses uniformly untilreaching the center portion and covers the entire surface of the heatsink 2.

Further, the cooling air blown out from the cooling fan unit 3 strikesthe base end of the heat-radiating fins, that is, the base surface 12 ofthe heat sink 12, then as shown by the arrow marks in FIG. 23(B), passesthrough the plurality of the heat-radiating fins 4,4 . . . and isdischarged to the outside from the outer circumferential edge of theheat sink 2, thereby cooling heat sink 2 in the process. At this time,the partition plate 31 restricts the path of discharge of the coolingair to the outside of the heat sink 2 and prevents a reduction of thecooling efficiency by the mutual collision of the cooling air.

Note that above the case was shown of provision of the partition plate31 at the heat sink 2 and formation of the clearance 32 enclosed by theenclosing wall 33 between the heat sink 2 and the cooling fan unit 3,but it is also possible to improve the cooling efficiency withoutforming the clearance 32 between the heat sink 2 and the cooling fanunit 3 and just providing the partition plate 31 at the heat sink 2.

Further, the partition plate 31 is not necessarily limited to one of across shape as shown in FIG. 23(B). It may be a linear or Y-shape or anyother suitable shape so long as it can radially and equally section offthe surface of the heat sink 2.

Further, in the above embodiment, the enclosing wall 33 is formed by acylinder separate from the heat sink 2 and the cooling fan unit 3, butit is not limited to this. It may also be formed integrally in advanceat the heat sink 2 side or the casing 3a side of the cooling fan unit 3.Also, use may be made of a band-shaped member.

As clear from the above explanation, according to the heat-generatingelement cooling device of the present 35 invention, it becomes possibleto make effective use of the cooling air from the cooling fan unit andpossible to improve the overall cooling efficiency.

A seventh embodiment of the heat-generating element cooling deviceaccording to the present invention is shown in FIG. 24. In thisembodiment, the heat-radiating fins 4 of the heat sink 2 are formed withthe opposing two side surfaces inclined to form a pointed shape. Notethat the cooling fan unit 3 has a motor 3c and fan blades 3d.

The present embodiment improves the cooling efficiency by facilitatingthe transfer of the cooling air from the cooling fan unit 3 to the basesurface 12 of the heat-radiating fins. If the sectional area of theheat-radiating fins 4 is made smaller the further toward the front end,the shape does not necessarily have to be pointed, but to promote theintroduction of the cooling air to the base surface 12 of theheat-radiating fins, it is preferable at least that the total area ofthe front end of the heat-radiating fins 4 be less than 20 percent ofthe overall area.

Further, in the above-mentioned embodiment, the inclined surfaces facethe same direction, but formation of the inclined surfaces so as to facethe center of the heat sink 2 is a preferable modification. Further, thesectional shape of the heat-radiating fins 4 may be rectangular,circular, or various other shapes.

A eighth embodiment of the heat-generating element cooling deviceaccording to the present invention is shown in FIG. 25. In theembodiment explained below, the effective amount of air of the coolingfan unit 3 is made to increase by reducing as much as possible thepressure loss of the cooling air blown from the cooling fan unit 3, soin the illustrated embodiment, the heat-radiating fins 4 on the heatsink 2 are arranged in a state occupying every other intersection of amatrix-like grid, that is, in a staggered manner.

An ninth embodiment of the heat-generating element cooling deviceaccording to the present invention is shown in FIG. 26. This embodimentdisposes auxiliary fins 41 with a small sectional area on theintersections of the grid not occupied by heat-radiating fins in theseventh embodiment mentioned above, so it is possible to increase theheat radiating area without increasing the pressure loss of the coolingair.

Further, in this embodiment, as shown in FIG. 27, when disposingheat-radiating fins 4 in the same way as the usual heat sink 2 on thegrid of the outer circumferential portion, passage of the cooling airabove the heat sink 2 without contributing to cooling is prevented andtherefore the cooling efficiency is improved further.

FIG. 28 gives a front cross-sectional view (A) and a top view (B) of theconstruction of a 10th embodiment of the heat-generating element coolingdevice according to the present invention, while FIG. 29 is a sectionalview along the section A--A of FIG. 28(B). This embodiment has aheat-generating element cooling device 10 comprised from an integralconstruction of the direct vertical mounting type fan and heat sink asshown in FIG. 28(A). Reference 1 shows for example an LSI package orother heat-generating element, 2 shows a heat sink formed by a materialwith a good heat conductivity, 4, . . . and 4-1, . . . showheat-radiating fins of the heat sink 2, 3 shows a small sized fan unitespecially for the high heat-generating element, 3c shows a fan motor,3d shows main blades, and 3e shows auxiliary blades. Note that thedotted arrow marks in the figure show the flow of the cooling air, thatis, the air flow. The air flow illustrated is that of the case of thesuck in type (pull system). In the case of the blow out type (pushtype), the air flow becomes the reverse direction.

In a construction such as the direct vertical mounting type where thefan rotational portion is in close proximity with the top of the heatsink (or the bottom), that is, the fan unit 3 and the heat-radiatingfins 4, . . . face each other, the portion directly under the motor 3cbecomes a cooling dead zone. Usually, the high temperature portionconcentrating at the center portion is not directly cooled, so thecooling efficiency is reduced.

In particular, giving an explanation taking as an example the case of anLSI package, the circuit boards in recent high density mountingequipment such as personal computers and work stations are disposed at ahigh density at close intervals. In the case of a construction such asthe direct vertical mounting type where the LSI package, that is, theheat-generating element 1, the heat sink 2, and the fan unit 3 arestacked over each other, the heat sink 2 cannot be formed thick.Therefore, the heat radiating effect from the center portiondeteriorates and the center portion becomes high in temperature. Thereis the problem that the temperature distribution from the center portionof the heat-generating element 1 to the peripheral portions thereofcannot be made not to be greatly changed, that is, it is not possible tomake sufficient "heat spreading". In addition, in the case of a ceramicpackage such as used for ordinary LSI packages, compared with an AlN(aluminum nitride) package etc., judging from the heat conductioncharacteristic, the spreading of heat at the generation of heat isessentially not sufficient and the spreading of the heat of theheat-generating element 1 is further inhibited.

In such a direct vertical mounting type cooling structure withinsufficient heat spreading, the high temperature portion is located atthe dead zone and therefore a reduction of the cooling efficiency iscaused. This embodiment is for improving this point. Therefore, as shownin FIG. 28, provision is made of auxiliary blades 3e, . . . at thebottom of the fan motor 3c. FIG. 29 is an enlarged cross-sectional viewof the center portion of the front sectional view of the coolingstructure of the direct vertical mounting type shown in FIG. 28. Shownthere are the air flows (a) and (b) in the pull system and theconstruction of the auxiliary blades 3e and the center portion fins 4-1.

The auxiliary blades 3e, as illustrated, are attached beneath of the fanmotor 3c, but to disperse the air of the dead zone well, they may beprovided suspended down or extended to the width of the heat sink 2 inthe thickness direction, suitable intervals, for example, severalmillimeters, may be provided between the auxiliary blades 3e and baseportion of the heat sink 2, and short fins 4-1, . . . may be disposedbetween them to maintain the heat radiating effect at the center portionof the heat-generating element 1. FIG. 30(A) to FIG. 30(G) are bottomviews illustrating various shapes of auxiliary blades 3e. These bladesare disposed radially from the center of rotation, but include not only(A), (B), (C), and (G) disposed with point symmetry, but also (F) notnecessarily point symmetric and (D) and (E) provided only partially.

According to this embodiment, the dead zone portion is agitated by theauxiliary blades 3e and the air is discharged outside by centrifugalforce, whereby as shown in FIG. 29, air flows (b) are created at thedead zone of the center portion and dispersion of heat is promoted. Bythis, along with the air flows (a) pulled out from the peripheralportions to the center portion by the fan main blades, the heatdispersion of the heat-generating element 1 is equalized and spreadingof the heat of the heat-generating element 1 is promoted. Further, thecooling efficiency can be made higher. Also, according to theconstruction of this embodiment, it is possible to use a lower speed fandue to the improved cooling efficiency, so the noise of the equipmentcan be reduced and further a contribution may be made to a prolongedlifetime of the equipment as a whole.

Note that the cooling structure of this embodiment is particularlyeffective when used for the pull system, but also exhibits a significanteffect even for the push system.

FIG. 31 shows a 11th embodiment of the heat-generating element coolingdevice according to the present invention, wherein (A) is across-sectional view, (B) is a side sectional view, and (C) is a planview. In this embodiment, the heat-generating element cooling device 10is comprised of a heat sink 2 formed by a material with good heatconductivity such as an aluminum material and a cooling fan unit 3formed integrally.

The cooling fan unit 3 drives the rotation of the fan blades 3d by amotor 3c disposed at the center portion and blows cooling air downward.It is mounted above the heat sink 2 by a suitable means, not shown. Onthe other hand, the heat sink 2 is formed with a plurality of pin-shapedheat-radiating fins 4, 4 . . . projecting from its top surface and isjoined to the heat sink surface of the heat-generating element using aheat conductive compound or adhesive.

In this embodiment, the heat-radiating fin base surface 12 of the heatsink 2 is formed by two inclined surfaces in a V-shape so that thecenter line of the heat sink 2 becomes the bottommost point. It is givena valley-like depression which becomes lower the further to the centerline.

Note that in the illustrated embodiment, the heat-radiating fin basesurface 12 is given a downward slope toward the center line along withthe V-shape, but it is not limited to this. It is also possible to formit so it becomes lower along a curved surface etc. toward the centerpoint. Further, it is not limited to a valley-like depression. It mayalso be formed to a conical or pyramidal depression.

FIG. 32(A) shows a modification of the embodiment mentioned above. Inthis modification, a linear partition plate 40 is provided on the centerline of the heat sink 2. This partition plate 40 functions both tosuppress the interference of the cooling air from the two ends and atthe same time as a heat-radiating fin 4. Further, as shown in FIG.32(B), by providing an L-shaped heat-radiating fin-cum-guide plate 42 atthe center portion, it is possible to collect the surrounding coolingair at the center.

FIG. 33 gives a top view, front view, and side view of the constructionof an 12th embodiment of the heat-generating element cooling deviceaccording to the present invention, while FIG. 34 is a frontcross-sectional view along the section A--A of FIG. 33. This embodimentalso has an integral construction of a direct vertical mounting type fanand heat sink as shown in FIG. 4(A). Only the construction of the heatsink 2 having the heat-radiating fins 4 and the fan unit 3 is shown. Theheat-generating element 1 is omitted. In this embodiment, further, asshown by the dotted arrow marks in FIG. 34, use is made of a push systemwherein the cooling air is blow to the heat-radiating fins 4, . . . andair flows (c) are caused.

In this embodiment, to lighten the reduction in the cooling efficiencydue to the dead zone in a direct vertical mounting type coolingstructure similar to that mentioned above, the base surface 12 of theheat sink 2 is inclined conically or pyramidally so that the centerportion becomes lower and the heat-radiating fins 4, . . . are formed sothat the heat-radiating fins 4-2 at the center portion become longerthan those at the peripheral portions. By this, a difference in thefluid pressure is created between the peripheral portions and the centerportion and the cooling air is collected at the center portion. At thesame time, as shown in FIG. 33 and FIG. 34, a heat pipe 50 is disposedfor example in a spiral shape along the inclined base surface 12 and toextend over the entire surface from the center portion to the peripheralportions. Further, as the method of mounting the heat pipe 50, there arethe buried mounting method where a groove is provided in advance in thebase surface 12 of the heat sink 2 and the method of directly laying andsoldering it on the base surface 12.

FIG. 35 gives a top view, front view, and side view of a modification ofthe embodiment. In this modified embodiment, the base surface 12 of theheat sink 2 is formed by two inclined surfaces 12-1, 12-1. The heat pipe50, for example, as shown in the figure, is disposed so that the mainheat pipe 51 is placed at the bottom of the V-section base surface 12-1and the sub-heat pipes 52, . . . are connected in accordance with theinclination of the base 12-1 from there.

According to the cooling structure of this embodiment, due to theconstruction of the heat sink 2 having the inclined base surface 12 or12-1, the cooling air is pulled toward the center portion of theelement. Also, by lowering the resistance of the blowing of the centerportion, the air speed is increased and the radiation of hightemperature at the center portion of the element where heat spreading isinsufficient is promoted. Also, the high temperature of the centerportion is conducted by the heat pipe 50 or 51 and 52 to the relativelylow temperature portions around the element to disperse the heat emittedat the center portion to the surroundings. By this, the heat spread ofthe heat-generating element 1 is further promoted. Also, by the rise ofthe temperature of the outer circumferential portions of the heat sink,the amount of heat radiated to the outside increases and therefore thecooling efficiency is improved.

Note that as a modification of the base surface 12 of the heat sink 2formed in a conical shape or pyramidal shape in this embodiment, thismay be formed in a spiral step shape and the heat pipe 50 may bedisposed along the steps. The heat pipe 50 may also be disposed radiallyalong the conically or pyramidally shaped base surface 12. Further, thecooling structure of this embodiment is particularly effective when usedfor the push system, but can also exhibit a significant effect for thepull system.

FIG. 36 and FIG. 37 show a 13th embodiment of the heat-generatingelement cooling device according to the present invention. In thefigure, 1 shows a heat-generating element mounted on a printed circuitboard, above which a cover member 22 is disposed.

In this embodiment, the cover member 22 has a cover 60 affixed to theheat-generating element 1. On its top surface is mounted a fan unit 3 sothat the blowing outlet of a fan is in register with the blowing openingmade at a suitable location of the cover 60. The fan unit 3 is formedwith a blowing fan accommodated in a casing 3a. To enable replacement atthe time of a breakdown, the unit is mounted to the cover 60 by screwsetc. at the four corners of the casing 3a or on diagonals of the same.

Further, so the cooling air blown from the fan blows directly againstthe high heat emitting portion 100 of the heat-generating element 1shown by the broken line in FIG. 37, the fan unit 3 is provided offsetwith respect to the center of the heat-generating element 1, that is, isdisposed off-center, so that the blades 3d of the fan come directlyabove the high heat emitting portion 100.

The cover 60 supporting the fan unit is formed by injection molding by aplastic material or by bending sheet metal. At the side edges of the twosides of the corner which the fan unit 3 is placed in close proximitywith due to the fan unit 3 being disposed off-center, a separating wall61 is formed by bending etc. along approximately two-thirds of each ofthe side edges.

Here, the cover member 22 mounting the fan unit 3 is adhered to the topsurface of the heat-generating element 1 so as to be affixed on theheat-generating element 1 by the flange 62 (see FIG. 36) formed bybending inward the bottom edge of the separating wall 61 and theauxiliary supporting portion 63 provided at a diagonal position withrespect to the separating wall 61. In this construction, part of theside edge between the heat-generating element 1 and the cover 60 of thecover member 22 is closed by the separating wall 61. At the remainingpart of the side edge is formed the clearance 70 serving as the exhaustopening 71.

Accordingly, in this embodiment, if the fan unit 3 is driven to blow thecooling air to the clearance 70 such as with the push system, forexample, the cooling air is blown downward toward the top surface of theheat-generating element 1 to cool the heat-generating element 1, thenflows outside from the exhaust opening 71. At this time, the separatingwall 61 prevents the cooling air from being immediately dischargedoutside from the clearance 70 without contributing to the cooling. Thecover 60 functions to reflect back to the heat-generating element 1 sideagain the cooling air reflected back after striking the heat-generatingelement 1. These both contribute to the improvement of the coolingefficiency.

Note that in this embodiment, the case is shown where the fan unit 3 isprovided at a position offset from the center of the heat-generatingelement 1 so that the cooling air from the fan unit 3 will directly blowagainst the high heat emitting portion 100 of the heat-generatingelement 1, but when a sufficient amount of cooling air can be suppliedfrom the fan unit 3, the fan unit 3 may also be disposed at the centerof the heat-generating element 1. In this case, preferably theseparating wall 61 is provided at the side edges so that the cooling airpasses through the clearance 70 as a whole.

FIG. 38 shows a 14th embodiment of a heat-generating element coolingdevice according to the present invention. The cover member 22 accordingto this embodiment is formed by a material with a good heat conductivitysuch as sheet metal. At the back side of the cover 60 spring members 64are affixed at suitable locations. The spring members 64 are formed of amaterial with a good heat conductivity and a good spring characteristicsuch as phosphor bronze. Their free height is made somewhat higher thanthe height of the clearance 70.

Accordingly, in this embodiment, in the state with the cover member 22attached to the heat-generating element 1, the spring members 64elastically deform and their free ends press against the top surface ofthe heat-generating element 1, so a heat path is formed conducting heatfrom the heat-generating element 1 through the spring members 64 to thecover member 22. As a result, the heat-generating element 1 is cooled byconduction by the heat path in addition to the cooling by the coolingair from the fan unit 3 and the cooling efficiency is improved more.Note that in this case, to improve the heat conduction of the centerportion of the heat-generating element 1, that is, the high heatemitting portion 100, the spring members 64 are preferably provided inclose proximity with the center of the heat-generating element 1.

FIG. 39 shows a 15th embodiment of the heat-generating element coolingdevice according to the present invention. The cover 60 in thisembodiment is provided with a plurality of ridges 72, 72 . . .projecting out at the clearance 70 side. These ridges 72 throttle thecooling air passing through the clearance 70 to raise the speed of thecooling air. Further, as shown in FIG. 39(C), they are provided so thatthe direction of the cooling air is made toward the surface portion ofthe heat-generating element 1, so these are disposed along the sideedges of the fan unit 3.

Next, a 16th embodiment of the heat-generating element cooling deviceaccording to the present invention is shown in FIG. 40. In thisembodiment, the heat sink 2 is mounted on the heat-generating element 1.On the top surface of the heat sink 2 are provided a plurality ofpin-shaped heat-radiating fins 4, 4 . . . . Fan units 3 are mountedabove this. Two fan units 3 are mounted at diagonal positions withrespect to the high heat emitting portion 100 and so that the blades 3dof the fan cover the high heat emitting portion 100. These are driven torotate in opposite directions.

Accordingly, in this embodiment, the cooling air blown from the two fanunits 3 merge at the high heat emitting portion 100 to increase theamount of air as shown by the arrow marks in FIG. 40(A). Note that atthe opposing corners of the heat sink 2, as shown in FIG. 41, L-sectionshaped side walls 43 corresponding to the side edges of the fan units 3are formed so as to prevent the cooling air from being discharged to theoutside of the heat sink 2 immediately without contributing to thecooling.

Further, FIG. 40 shows the case of disposing the fan units 3 at diagonalpositions, but in addition, as shown in FIG. 42, it is possible todispose two fan units 3, 3 aligned on the center line L of theheat-generating element 1. Further, the number of the fan units 3 is notlimited to two. Three or, for example, as shown in FIG. 43, four, oreven more may be provided. In any case, the fan units 34 are driven sothat the cooling air collects at the center of the heat-generatingelement 1 as shown by the arrow marks in the figures. Also, the heatsink 2 is provided suitably with side walls 43 for preventing thecooling air from immediately being discharged outside of the heat sink 2without contributing to the cooling.

FIG. 44 and FIG. 45 give views of a 17th embodiment of theheat-generating element cooling device according to the presentinvention. This embodiment is a modification aimed at reducing themounting height. In it, the heat sink 2 is affixed on the printedcircuit board 16 adjoining the heat-generating element 1. A heat pipe 55is laid between the heat sink 2 and the heat-generating element 1. Inother words, the heat radiator portion is constructed disposed away fromthe heat-generating element 1.

The heat pipe 55 is formed by a copper pipe in which is sealed a workingfluid such as a chlorofluorocarbon. One end is affixed to the topsurface of the heat sink 2 and the other end is affixed to theheat-generating element 1. This heat pipe 55 is formed in a flatfork-shape branching at the heat sink 2 side so as to be directly struckby the cooling air from the fan unit 3 and cool above the high heatemitting portion 100 of the heat-generating element 1 at theheat-generating element 1 side. To house one end of the fork, the heatsink 2 is formed with a space 45 for fitting it where no pin-shapedcooling fins are provided. On the other hand, the heat-generatingelement 1 side is mounted on the top surface of the heat-generatingelement 1 sandwiched in between the base plate 65 affixed using forexample an adhesive with a good heat conductivity and a fixing plate 66screwed to the base plate 65.

By this construction, if the heat-generating element 1 emits heat, theworking fluid inside the heat pipe 55 boils and absorbs the heat emittedby the heat-generating element 1. The bubbles caused by the boiling arecooled at the heat-radiating fin 4 side to liquify and are returned tothe heat-generating element 1 side.

In this case, when the exhaust temperature from the heat sink 2 is low,as shown by the double line in FIG. 46(A), it is preferable to close theside edge of the side opposite to the heat-generating element 1, makethe exhaust positively flow to the heat-generating element 1 side, andsuppress the rise in temperature of the fixing plate 66. Conversely,when the exhaust temperature is high, as shown in FIG. 46(B), it ispreferable to close the side edge of the heat-emitting element 1 side toprevent a rise in temperature of the heat-generating element 1 by theexhaust.

Further, it is possible to provide irregularities or heat-radiating finsat the top surface of the fixing plate 66 so as to assist the radiationof heat from the heat-generating element 1.

Further, to make the heat conductivity between the fixing plate 66 andthe base plate 65 good, for example, as shown in FIG. 47 and FIG. 48, itis preferable to provide at the opposing faces of the fixing plate 66and the base plate 65 irregularities of a rectangular wave or sawtoothsectional shape and to engage the same. In the case of such aconstruction, as shown in FIG. 47(B), it is also possible to provide aclearance 67 at the engagement portion of the irregularities and topositively introduce cooling air there from the fan unit 3. On the otherhand, the method of fixing the heat pipe 55 to the heat sink 2 is notlimited to the method shown in FIG. 45. For example, it is also possibleto affix it through the affixing fitting 52 shown in FIG. 49.

That is, the affixing fitting 56 is formed by a material with a goodheat conductivity and is provided with pipe holding grooves 56a whichpush the fork of the heat pipe 55 upward and affixing legs 56b formed attheir top ends with bent flanges 56c.

This affixing fitting 56 is affixed to the heat sink 2 by fastening theflanges 56c together with the fan unit 3 to the heat-radiating fins 4 orspecially provided support columns positioned at the four corners of theheat sink 2. In this state, the forked portion of the heat pipe 55, notshown, is sandwiched between the top surface of the heat sink 2 and thepipe holding grooves 56a. Note that in FIG. 49 an illustration of theheat-radiating fins 4 was omitted, but these are suitably provided asrequired.

Note that in the above-mentioned embodiment, the case was shown of asingle fan unit 3 placed on the heat sink 2, but it is of course alsopossible to provide the heat pipe at the center and provide two fanunits at diagonal positions as shown in FIG. 50.

As clear from the above explanation, according to the present invention,the heat-generating element is concentratedly cooled using the fandevice, so the cooling efficiency can be remarkably improved.

As mentioned above, in the case of an LSI package, the circuit boards ina work station and other recent high density mounting equipment aredisposed at intervals of slightly over 20 mm. There are limits to howfar this can be handled by a direct vertical mounting type coolingstructure. For example, if the thickness of the LSI package is 5 mm, thethickness of the heat sink is 5 mm, and the thickness of the thinnestfan at present is 10 mm and if consideration is given to the projectionof the IC socket, then the combined thickness of the heat sink and thecooling fan must be made about 10 mm and the overall thickness combinedwith the package must be about 15 mm. Therefore, consideration has beengiven to the buried mounting type cooling structure such as shown inFIG. 4(B).

FIG. 51 gives a top view, front view, and side view of the constructionof the heat-generating element cooling device of the buried mountingtype. Here, 2 shows a heat sink, 3 a fan unit, and 75 a cover. Theheat-generating element 1 is omitted. FIG. 52 gives partial enlargedcross-sectional views of the center portions in the section along thesection A--A in FIG. 51. As illustrated, the fan unit 3 is mounted so asto be buried in the width of the heat sink below the air intake andexhaust opening 76 formed in the cover 75 covering the heat sink 2. Theheat-radiating fins 4 of the heat sink 2 are disposed around the fanunit 3. In the figure, 3c is a fan motor, 3d fan main blades, 35 a coil,36 a magnet, 37 a fan motor bearing, and 38 circuit components and aboard. Note that the cover 75 has formed at it a cylindrical member 77connected to the air intake and exhaust opening 76. This surrounds themounted fan unit 3 and guides the cooling air and also constitutes athrottling mechanism which throttles the cooling air by the clearancewith the base surface 12 of the heat sink 2.

FIG. 52(A) gives a partial enlarged cross-sectional view of a buriedmounting type cooling structure of the usual pull system. The cover 75supports the fan unit 3 by supporting spokes 78, . . . . For example, asshown in FIG. 51, it is supported by supports at four corners of theheat sink 2. Below the fan motor 3c is formed the above-mentioned deadzone DZ. Further, above it, the fan motor driving circuit components andboard 38 are attached to the fan motor bearing portion. FIG. 52(B) likeFIG. 52(A) gives a partial enlarged cross-sectional view of a buriedmounting type cooling structure. Here, the fan unit 3 is supported atthe base surface 12 of the heat sink 2. Further, the circuit componentsand board 38 are attached below the fan motor 3c. Otherwise, theconstruction is similar to that of FIG. 52(A). In this way, no matterwhich construction is adopted, in a buried mounting type coolingstructure, the fan motor driving circuit components and board 38 aremounted above or below the fan motor 3c and the thickness of the fanunit ends up being increased by that amount.

FIG. 53 gives a top view, front view, and side view of the constructionof a 18th embodiment of the heat-generating element cooling deviceaccording to the present invention, while FIG. 54 gives partial enlargedcross-sectional views of the center portion in the section along thesection A--A in FIG. 53. These show two constructions: the construction(A) where the fan unit 3 is supported at the cover side and theconstruction (B) where it is supported at the heat sink side. As clearfrom these figures, in this embodiment, the fan motor driving circuitcomponents and board 38 are mounted on the cover 75 as shown in FIG.54(A) or are mounted on the base surface, for example, of the heat sink2 as shown in FIG. 54(B). At this time, the Hall element 39 for drivingthe cooling fan is mounted separately on the cover or at a positionfacing the fan motor 3c on the heat sink.

According to the cooling structure of this embodiment, the fan motor 3cis made longer and smaller in diameter by the amount of space obtainedby removing the circuit components and board 38 from above the fan motor3c as shown in FIG. 54(A) showing the construction with the fan unit 3supported on the guide 75 side or the amount of space obtained byremoving the circuit components and board 38 from below the fan motor 3cas shown in FIG. 54(B) showing the construction with the fan unit 3supported on the heat sink 2 side, so the region of the dead zone DZshown in FIG. 52(A) can be shrunken. By this, the cooling efficiency isimproved and accordingly it becomes possible to obtain an equivalentcooling capacity by a slower speed fan. The noise is lightened alongwith this and a contribution is made to the prolongation of the lifetimeof the equipment.

FIG. 55 gives a top view, front view, and side view of the constructionof a modification of the embodiment of FIG. 53 and FIG. 54. FIG. 56gives partial enlarged cross-sectional views of the center portion alongthe section A--A in FIG. 55. This shows two constructions: theconstruction (A) where the fan unit is supported at the cover 75 sideand the construction (B) where it supported at the heat sink 2 side. Inthis modified embodiment, the disposition of the circuit components andboard 38 and the Hall element 39 is similar to the case of FIG. 53 andFIG. 54, but the thickness of the fan unit 3 is reduced by the amount ofspace obtained by removing the circuit components and board 38 fromabove the fan motor 3 as shown in FIG. 56(A) or the amount of spaceobtained by removing the circuit components and the board 38 from belowthe fan motor 3c as shown by FIG. 56(B), whereby the integral fan typeheat-generating element cooling device can be made thinner inconstruction overall. By this, it becomes possible to use it for recenthigh density mounting type equipment and becomes possible to increasethe range of application of the integral fan type heat-generatingelement cooling device.

Note that as an other modification of the present embodiment, while notshown, it is possible to mount the circuit components and the board 38to the fan motor support spokes 78 of the cover, the casing of the fanmotor 3c, or the heat-radiating fins 4 of the heat sinks Further, in theillustrated embodiment and its modifications, use was made of the pullsystem of cooling structure, but of course it is also possible to applythis to the case of use of the push system. Further, wiring is necessarybetween the circuit components and board 38 and the fan motor 3c, but ifordinary wire is used for the wiring, the air resistance will beincreased, so for example the wiring may be performed by using flat,so-called flexible wiring strips and adhering them to the cover or thebase surface of the heat sink.

FIG. 57 and FIG. 58 give top views and front views of the constructionsof an overall device (A) and cover (B) for two examples of theheat-generating element cooling device having a cooling structure of anintegrated buried mounting type cooling fan and heat sink of theheat-generating element such as shown in FIG. 4(B). In the figures, 3shows a cooling fan unit, 2 a heat sink having a plurality ofheat-radiating fins 4, . . . , 75 a cover having an air intake opening76, and 78 fastening screws.

In the example of FIG. 57, a fan unit 3 is mounted in a buried manner inthe center portion of the heat sink 2 attached to the top surface of anLSI package or other heat-generating element by for example an adhesiveor affixing fitting. The fan unit 3 is accommodated in the air intakeopening 76 provided at the center portion of the cover 75 and inside thecylindrical projection portion 77 connected to the same. Thiscylindrical projection portion 77 has a predetermined clearance with thebase surface 12 of the heat sink 2 and forms a throttling mechanism. Theair sucked from the air intake opening 76 by the fan unit 3 passesthrough the throttling mechanism and, as shown by the dotted arrow marksin FIG. 57(A), forms the air flow for cooling. The cover 75 is affixedby fastening screws 78, for example, at the four corners to thesupporting blocks 79, . . . formed at the four corners of the heat sink2.

In the example of FIG. 58, the construction is similar to that of theexample of FIG. 57, but the fan unit 3 and the air intake opening 76 ofthe cover 75 facing it are offset from the center portion of the heatsink 2 in the direction of one corner, that is, are disposedoff-centered. In a thin type cooling device for high density mounting,the heat sink 2 becomes thinner and so the heat emitted at the centerportion of the heat-generating element cannot be sufficiently conductedto the surroundings, so the temperature distribution becomes one of ahigh temperature at the center portion and a low one at the peripheralportions, that is, an uneven heat spread results. The presentconstruction is adopted so as to raise the cooling efficiency of thehigh temperature portion at the center and to avoid a reduction of thelifetime of the bearings of the fan motor due to the high temperature.Note that in this embodiment, the supporting block 79' at the cornerwhich the fan unit 3 is in close proximity with is formed with a widewidth and the air flow is directed toward the center portion.

According to the integral fan type heat-generating element coolingdevice of the above construction, since the fan unit 3 is buried, theintake air is discharged to the outside before sufficiently contributingto the cooling, so there is the problem that the cooling efficiency islow.

FIG. 59 gives a top view and front view of the construction of an 19thembodiment overall (A) and a cover (B) of the heat-generating elementcooling device according to the present invention. Further, FIG. 60gives structural views of the construction of just the heat sink in theembodiment of FIG. 59. This embodiment has a similar construction withthe cooling structure of the conventional device shown in FIG. 57 withthe fan unit 3 disposed at the center portion of the heat sink 2.Equivalent members in FIG. 59 and FIG. 60 are given the same references.

In this embodiment, however, the cover 75 is not provided with thecylindrical projecting portion 77 forming a throttling mechanism asshown in FIG. 57, but has a cylindrical member 80 supported bysupporting legs 81, . . . provided on the base surface 12 of the heatsink 2 disposed as the throttling mechanism. FIG. 61 is an enlargedperspective view of the construction of the throttling mechanism portionon the heat sink 2. As clear from FIG. 60 and FIG. 61, a clearance isformed between the cylindrical member 80 and the base surface 12 of theheat sink 2 and the cooling air passes through this clearance.

The cylindrical member 80 and the supporting legs 81, . . . are formedby a material with a good heat conductivity and increase the surfacearea for radiating heat from the heat sink 2. Accordingly, these can beformed of the same material as the heat sink 2. Further, they can beformed integrally. If the cylindrical member 80 and the supporting legs81, . . . are formed integrally in this way, then it is possible todispose the heat-radiating fins 4, . . . in close proximity in thesurroundings and raise the density of disposition. Further, as shown inFIG. 61, the outer surface of the cylindrical member 80 including theinside and outside circumferences is provided, for example, with finegrooves 82, ridges, or other irregularities. Further, the surface areafor heat radiation may be increased.

This embodiment being constituted in this way, it is possible to makeuse of the throttling mechanism which had been attached to the cover inthe conventional device so as to effectively radiate heat from the heatsink 2. Further, by having air flow at a high speed among the pluralityof supporting legs supporting the throttling mechanism, the coolingefficiency can be further raised, which is helpful in improving thecooling efficiency of the cooling device as a whole. Also, the spacewhich had been required for fitting the throttling mechanism attached tothe cover into the heat sink in the conventional device mentionedearlier becomes unnecessary and so that many more heat-radiating finscan be added and therefore it is possible to contribute to theimprovement of the cooling efficiency of the cooling device as a whole.

Next, as mentioned earlier, the heat sink 2 is attached on the LSIpackage or other heat-generating element by an adhesive or affixingfitting. If the entire surface s adhered with an adhesive, however, heatstress will occur due to the difference in the coefficient of heatexpansion of the element and the heat sink 2 and there will be thedanger of cracks occurring in the element. Further, if the entiresurface is adhered by an adhesive sheet etc., since there is no fluiditycompared with an adhesive, clearance will be caused by the difference inplanarity and there will be the problem of easy peeling. In addition, ifaffixed by a fitting etc., sockets become necessary or the board must beprocessed, so there is the problem of numerous limitations in mounting.

FIG. 62 gives a top view and front view of the construction of a 20thembodiment of the heat-generating element cooling device according tothe present invention. This embodiment illustrates the case where theheat-generating element and the heat sink are circular, but has asimilar construction as the cooling structure of an off-centered typecooling device wherein the fan unit 3 shown in FIG. 58 is disposedoffset from the center portion of the heat sink 2. The same referencesare given to equivalent members or else the references are omitted. Notethat the illustration of the fan unit 3 is omitted, but its backportion, that is, the edge of the heat sink 2 at the side where noheat-radiating fins are disposed is provided with the side wall 79" soas to prevent the escape of the cooling air. Further, the cover 75 isattached to the heat sink 2 by adhesion or another method. Theattachment blocks 79 and fastening screws 78 are eliminated.

In this embodiment, near the center of the heat sink 2 is formed afemale screw portion 85 in which is screwed the male screw affixed tothe heat-generating element from the bottom surface. The female screwportion 85 rises from the base surface 12 of the heat sink 2 and extendsinto the space occupied by the heat-radiating fins 4, . . . . In thisway, the female screw portion 85 is exposed to the cooling air in theinside of the heat sink 2 and functions to assist the heat radiation.Therefore, the female screw portion 85 is formed with a shape with alarger surface area so as to enable the heat radiating effect to beraised. Further, as shown in FIG. 62, the heat-radiating fins 4 aroundthe female screw portion 85 are made intermittent to reduce the pressureloss at the time of passage of the cooling air and therefore ensure theamount of the cooling air.

FIG. 63 gives a top view and front view of the construction of anexample of a male screw member 86 disposed on the top surface of theheat-generating element. The male screw member 86 is formed by amaterial with a good heat conductivity. For example, it has a screwportion 86' which screws into a female screw portion 85 provided in theheat sink 2 of FIG. 62 and a flange portion 87 affixed by adhesion oranother method to the top surface of the heat-generating element. Bythis male screw and female screw, it is possible to tightly join theheat-generating element and the heat sink 2 with the cooling fan mountedon it. Using this tightening force, it is possible to reduce the contactheat resistance between the same. Note that the male screw member 86 mayalso be formed integrally with the top surface of the heat-generatingelement.

FIG. 64 gives cross-sectional views in the section A--A of FIG. 63 forshowing various examples of the construction of male screw members. Themale screw member 86 efficiently conducts heat emitted from theheat-generating element to the female screw portion 85. This heat isradiated in the cooling space of the heat sink 2. Therefore, the coolingof the heat-generating element is assisted. Accordingly, theconstruction is also good in heat conductivity. That is, the male screwmember 86 may not only be formed by a single material with a good heatconductivity such as shown in FIG. 64(A), but as shown in FIG. 64(B), itmay be constructed having a peripheral portion 86" formed by brass and acenter portion 88 formed by pure copper. Further, as shown in FIG.64(C), it is possible to provide a cavity 88' inside and make a vacuumstate and fill a working fluid 89 serving as the heat pipe medium in thesame. By this, it becomes possible to use the principle of the heat pipeto increase the amount of heat transfer.

Since this embodiment is constructed in this way, it is possible toavoid the cracking and peeling phenomena caused by the thermal stresscaused at the joint between the heat-generating element and the coolingdevice in the conventional apparatus and further it is possible toassist the heat radiation of the heat-generating element as mentionedabove and as a result raise the cooling efficiency. Further, it ispossible to affix the integral fan type cooling device of the presentinvention by screws and thereby enable easy detachment of the coolingfan when broken and enable a higher reliability.

Next, FIG. 65 is a perspective view of the mounting state in the case ofmounting a plurality of such integral fan type heat-generating elementcooling devices in parallel, and FIG. 66 is a top view of the same. Inthe figure, 10, . . . are cooling devices, (a) is the cooling air flowof the equipment, and (b) is the air flow of the cooling devices. Insuch a mounting state, in particular when using the cooling device ofthe structure shown in FIG. 57, the air is exhausted in at least twodirections, so as shown in FIG. 66, the exhaust collides among theparallel arranged cooling devices 10, 10 and there is the problem thatthe overall cooling efficiency falls. In addition, if use is made of ahigh speed fan unit to compensate for the fall in the cooling efficiencymentioned above, the noise becomes relatively greater and the noiselevel of the equipment as a whole is pushed up.

FIG. 67 gives a top view, front view, and side view of the constructionof a 21st embodiment of a heat-generating element cooling deviceaccording to the present invention. The embodiment has a similarconstruction as the cooling structure with the fan unit 3 disposed atthe center portion of the heat sink 2 as shown in FIG. 57(A). Equivalentmembers are given the same references or references are omitted. In theembodiment, further, the cover 75 extends outward at one side edgedirectly above the heat sink 2 (or the heat-generating element belowit), forming an extension portion 75'. The front edge of this hangsdownward. A bent portion, that is, the shielding plate 90, is formed soas to be substantially parallel with the side surface of the heat sink2. Since this construction is adopted, as shown by the dotted arrows inFIG. 67, the air flow supplied from the fan unit 3 strikes the shieldingplate 90 and is reflected downward. While not shown, the air flow endsup striking the bottom surface of the heat-generating element at thebottom of the heat sink 2.

FIG. 68 is a perspective view of the mounting state in the case ofmounting a plurality of the heat-generating element cooling devicesaccording to this embodiment, and FIG. 69 is a top view of the same. Inthe figure, 10', . . . is a cooling device according to the embodiment,(a) is a cooling air flow for the equipment, and (b) is an air flow forthe different cooling devices. The cooling devices 10' are provided sothat the shielding plates 90 are parallel with the cooling air flow (a)of the equipment. As clear from FIG. 69, the shielding plates 90 areinterposed between the parallel arranged cooling devices 10', . . . andtherefore it is possible to avoid the interference of the air flows (b),. . . among the different cooling devices in FIG. 65 and FIG. 66.Therefore, according to this embodiment, it is possible to attain thedouble effect of enabling prevention of a reduction of the coolingefficiency caused by the collision of the exhausts among the coolingdevices when a plurality of them are provided and enabling improvementof the cooling efficiency by introducing the exhaust to the bottomsurface of the heat-generating element.

Note that as mentioned above, by providing the shielding plate 90 so asto be parallel with the cooling air flow (a) for the equipment, it ispossible to make the cooling air flow (a) for the equipment, pass in theheat sink even when the cooling fan of the cooling device stops.Further, while not illustrated, it is possible to form at least thebending portion of the shielding plate 90, that is, at least theconnection portion of the extension portion 75' and the shielding plate90 by a shape memory alloy or another shape memory material and to storea shape such as the same flat surface as the extension portion 75', thatis, a substantially flat plate, for high temperatures. By doing this,for example, when the cooling fan of one cooling device stops, it ispossible to open the shielding plate 90 when the heat-generating elementwhere this is mounted becomes high in temperature so as to suck in theair flow (b) of the adjoining cooling device.

Next, in the case of an LSI package mounted in a piece of recent highdensity mounting equipment as mentioned earlier, for example, higherdensity mounting is becoming necessary as in the case of shelves withfixed pitches as shown in FIG. 1, height restrictions such as withnotebook personal computers, etc. There are cases where mounting in theequipment is not possible depending on a cooling structure of the directvertical mounting type or a cooling structure of the buried mountingtype. An even thinner cooling structure is sought.

FIG. 70 gives a top view (A) and a front cross-sectional view (B) of theconstruction of a 22nd embodiment of the heat-generating element coolingdevice according to the present invention, devised to meet suchrequirements, and FIG. 71 is a perspective view of the same. Thisembodiment provides an integral fan type heat-generating element coolingdevice of the side mounting type wherein the fan unit 3 is disposed atthe side of an assembly of the heat-generating element 1 and the heatsink 2 and these are connected by a cover 91 prepared by a material witha good heat conductivity.

In the embodiment, the cover 91 of the material with the good heatconductivity has a portion formed integrally with the heat sink 2 oraffixed to it by screws etc. and covering the heat sink 2 and has anextension portion extending from the same and joined with the fan unit 3by screws or fitting and having an air intake and exhaust opening 92attached facing the fan unit 3. The three outside surface portions ofthe extension portion are closed by the side plates 93, . . . . Further,the bottom of the fan unit 3 is closed by the bottom plate 94. Note that95 is a spoiler plate, 96 a guide, 16 a board to which the LSI packageor other heat-generating element 1 is attached, and 97 a power supplypin to the fan unit 3. The fan unit 3 may be affixed to the board 16 bya plurality of pins including this power supply pin 97.

Since the embodiment is constituted in the above way, the cooling air issupplied by the push system. In the air flow shown by the dotted arrowsin FIG. 70, air is sucked in from the air intake opening 92 of the topsurface of the cover 91, is guided by a suitable spoiler plate 95 orguide 96 such as illustrated, is sent to the heat sink 2, and isexhausted from the end portion on the side opposite to the fan unit 3.

FIG. 72 is a top view of the construction of a first modified embodimentof the embodiment, and FIG. 73 is a perspective view of the same. Thisfirst modified embodiment has a similar construction as the integral fantype heat-generating element cooling device of the side mounting typeshown in FIG. 70 and FIG. 71. Constituent elements which are equivalentare given the same references. Further, in the modified embodiment, oneor more side plates 93 of the fan unit portion are provided withopenings 98, . . . as illustrated for example. The openings 98, . . .are provided at the back side of the fan unit 3, that is, the sidefurthest from the heat sink 2. By allowing part of the air to escape, arise in the air pressure at the back of the closed fan unit 3 isavoided, pressure loss of the fan is reduced, and the load is lightened,resulting in making it possible for a sufficient amount of air to besecured.

Also, in this embodiment, the cover 91 may be made to cover only the topsurface of the heat sink 2. Further, it may be made to close also theside surface of the heat sink 2 except for the side portion of the airintake and exhaust opening. FIG. 74 is a perspective view of theconstruction of a second modified embodiment of the embodiment. The twoside plates 93', 93' of the cover 91' are used to close the two sidesurfaces of the heat sink except for the end portion on the oppositeside of the fan unit 3.

Further, in the case of the embodiment shown in FIG. 70, as the LSIpackage of the heat-generating element 1, use is made of a cavity uptype with a semiconductor chip attached to the top surface of theelement, but in the case of a cavity down type of element where thesemiconductor chip is attached to the bottom surface of the element, ifthe cooling air is made to flow to the pin side with the shortconduction path from the chip, it is possible to raise the coolingefficiency over the case of making the cooling air flow to only the heatsink 2 side provided at the cap of the element 1. FIG. 75 gives a topview (A) and a front sectional view (B) of the construction of a thirdmodified embodiment of the embodiment. In the third modified embodiment,provision is made of a wedge-section shaped guide 96' so as to enablethe air flow to be branched to the top and bottom and provision is madeof air holes 99 at the bottom plate 94 of the fan unit portion. By this,an air flow is formed as shown by the dotted arrows in the figure, andcooling air is sent to the pin side of the heat-generating element 1, sothe cooling efficiency is raised.

FIG. 76 gives a top view (A) and a front sectional view (B) of theconstruction of a fourth modified embodiment of the embodiment. Here, asthe heat sink, instead of the rectangular one such as shown in FIG. 70to FIG. 75, use is made of a disk shaped heat sink 2' having stackedtype heat-radiating fins. The cover 91 is affixed by fitting to the twosides of the disk-shaped heat sink 2'. For example, as shown in FIG. 77showing the portion B of FIG. 76 enlarged, by providing a plurality ofdownward facing hooks 91a at the two side portions of the edges of thecover 91 and pushing in the cover 91 from above to engage with the edgesof the heat sink 2', it becomes possible to releasably attach the same.This makes it easy to detach the cover 91 and perform maintenance andinspection of the fan unit 3.

FIG. 78 gives a top view (A) and a front cross-sectional view (B) of theconstruction of a fifth modified embodiment of the embodiment and FIG.79 is a perspective view of the same. In this modified embodiment,instead of sucking in the air from the air intake opening of the topsurface of the cover shown in FIG. 70 to FIG. 77, provision is made ofan air intake and exhaust opening 92' at the bottom plate 94 of the fanunit portion so as to guide air from the clearance between the fan unitand the board 16 and suck it in from the air intake and exhaust opening92'. In this case, the air is taken in from below the fan, so thespoiler plate (95) becomes unnecessary. In this way, an air flow iscaused as shown by the dotted arrow marks in FIG. 78. In this case, thepressure loss in the air intake opening becomes higher compared withthat shown in FIG. 70 to FIG. 77, but the flow in the fan unit 3 becomessmoother.

In the embodiment shown in FIG. 70 to FIG. 79, the rotational shaft ofthe cooling fan in the fan unit 3 may be provided inclined so as toefficiently form the air flow heading from the air intake and exhaustopening through the cooling fan to the heat-radiating fins of the heatsink 2. That is, when the air intake and exhaust opening shown in FIG.70 to FIG. 77 is provided in the top surface of the fan unit 3, therotational shaft of the cooling fan is inclined leftward toward theplane of the drawing. Further, when the air intake and exhaust openingshown in FIG. 78 and FIG. 79 is provided in the bottom surface of thefan unit 3, the rotational shaft of the cooling fan is inclinedrightward toward the surface of the drawing. By this, it is possible toefficiently form an air flow from the air intake and exhaust opening tothe heat-radiating fins of the heat sink 2.

FIG. 80 to FIG. 82 give top views and front views of examples of thearrangement and shape of heat-radiating fins 4, . . . of the heat sink 2used in the present embodiment. As illustrated here, the area in whichthe heat-radiating fins 4 are disposed is just the portion directlyabove the heat generating portion of the element 1, not the entireregion of the heat sink 2, so it is possible to reduce the pressure lossby the heat sink and secure the necessary air speed. Also, it ispossible to provide guide walls 47, 47 at the two sides of the heat sink2 (FIG. 80 and FIG. 81), provide guide walls 48, 48 guiding to the heatgenerating portion of the element 1 (FIG. 82), or preventing the coolingair from passing through portions where the heat-radiating fins are notdisposed and from being exhausted to the sides and guiding the coolingair effectively to the heat-radiating fins 4, . . . disposed locally soas to improve the cooling efficiency.

In the explanation of the embodiment given above, use was made ofpin-type or stacked type heat-radiating fins of the heat sink, but theside mounted type cooling construction such as in this embodiment is notlimited to these. Use may effectively be made of various shapesincluding for example the plate shape. Further, as the cooling system, apush system is adopted where the air ejected from the fan is blownagainst the heat sink, but use may also be made of the pull system wherethe air passing over the heat sink is sucked in.

INDUSTRIAL APPLICABILITY

As explained above, according to the heat radiator of the presentinvention, it is possible to make effective use of the cooling air of acooling fan with limited power, so it is possible to raise the coolingefficiency. On top of this, there is no need for using a high poweredcooling fan, so it is possible to prevent the generation of noise.

Further, according to the integral fan type heat-generating elementcooling device according to the present invention, the advantages of thedirect vertical mounting type where the fan unit is mounted above theheat sink, the buried mounting type where the fan unit is buried in thecenter portion of the heat sink, and the side mounting type where thefan unit is disposed at the side of the assembly of the heat-generatingelement and the heat sink are made effective use of to improve thecooling efficiency and make the construction thinner. For example, ittherefore becomes possible to meet the recent demands for high densitymounting equipment such as personal computers, work stations, etc.

We claim:
 1. A heat-generating element cooling device comprising a heatsink disposed on a top surface of a heat-generating element and having abody, a base, a top surface and a plurality of heat-radiating finsdisposed on a surface of said base except at least at a fan mountingportion, a cover having an air intake and exhaust opening facing the fanmounting portion of said heat sink and attached so as to cover the topsurface of said heat sink, a cooling fan unit having fan blades andbeing mounted so as to be positioned beneath the air intake and exhaustopening of said cover and embedded within the body of said heat sink,andcircuit components for driving the fan unit separate from the fan unitand attached to at least one of an inner surface of said cover and aninner surface of said heat sink thereby reducing the thickness of thefan unit to ensure an air gap between the fan blades and the base and toimprove cooling efficiency.
 2. A heat-generating element cooling deviceas set forth in claim 1, wherein flat wiring strips are attached to atleast one of the inner surface of the cover and the inner surface of theheat sink for electrically connecting the circuit components for drivingthe fan unit thereby further reducing the air gap between the cover andthe heat sink.